Refractive correction is achieved through use of spectacle lenses, contact lenses, corneal refractive surgery and intraocular lens implantation. Contact lenses have evolved from non-gas-permeable rigid lenses which contact the sclera and vault the cornea to corneal contact lenses made of gas permeable products, and then to corneal-scleral contact lenses made of hydrogel materials. Hybrid lenses were created to provide the improved optics of rigid lenses with the comfort of soft lenses. Hybrid lenses were configured to have a central rigid zone joined at a radial junction to a peripheral hydrogel zone. Composite lenses have a full soft layer and those having only an annulus of soft posterior to the rigid layer have been anticipated.
Hybrid lenses of this configuration enjoy commercial success with limitations due to the separation of the two materials at their radial junction, lens flexure and tear stagnation due to a circumferential sealing of the lens against the underlying eye. Advanced manufacturing processes and ultra high gas permeable materials have stimulated a resurgence of fully rigid scleral lens designs.
Rigid, soft and composite lenses have been used or envisioned for corneal reshaping or corneal refractive therapy. Corneal refractive therapy appears to have value in changing the optics of the cornea with a concomitant benefit in regulating the development of the refractive error of the eye. Recent research points to the role of light or illumination in the regulation of the development of refractive errors of the eye.
Smith and co-workers reported results of exposure of the eyes of primates to peripheral illumination as an opposite to form deprivation and found that eyes having peripheral retinal illumination exposure experienced less axial length growth than those having a lower level of illumination. (E. L. Smith III, L. Hung and J. Huang, Protective Effects of high ambient lighting on the development of form-deprivation myopia in rhesus monkeys, Iovs, December 2011, http://www.iovs.org/content/53/1/421.abstract). Further, they found these effects to be regional indicating the possible specificity of peripheral illumination.
Pugh and co-workers are developing technology for the incorporation of electronics in contact lenses. (See U.S. Patent Publication Nos. 2010/0110372, 2010/0109175, 2010/0103369, 2010/0079724, 2010/0078838, 2010/0078837 and 2010/0076553). The primary focus of these electronics is for directing information content to the central retina and for sensing ocular information including correlates to blood sugar levels and intra-ocular pressure. A number of other applications can be anticipated including the measure of inflammatory mediators in the tear film and intra-ocular blood pressure, and equivalent oxygen percentage requirements of the cornea. Pugh and co-workers have anticipated the potential to manufacture lenses with microcontrollers and energy sources.
Tieppo and co-workers have developed nano-particle technology for the purpose of sustained drug delivery to the eye. (A. Tieppo, C. J. White, A. C. Paine, M. L. Voyles, M. K. McBride, M. E. Byrne, Sustained in vivo release from imprinted therapeutic contact lenses, Journal of Controlled Release, October 2011). It is anticipated that the measure of intra-ocular pressure will be coupled with the drug delivery. In the same manner, the measure of blood sugar by way of a contact lens is anticipated to be used to regulate implanted insulin pumps. Further, the measurement of inflammatory mediators can be used to regulate the administration of anti-inflammatory agents in a lens, orally or by way of implanted pumps. The use of contact lens measuring systems coupled to pharmaceutical delivery provides value in regulating a wide range of systemic and ocular conditions.
The increase in incidence and resultant prevalence of myopia in the developed world and most particularly in Asia presents a problem of epidemic proportion. The changes in life-style, living conditions and activity preferences often prevent the ability to engage in outdoor activities. Educational, vocational and avocational demands and habits generate a set of circumstances which replace the available time for exposure to ambient outdoor light. Further, the needs to conserve energy indoors may have an ongoing effect in reducing the ambient light levels inside homes and buildings.
Research supports that the mechanism for the development of refractive error is multivariate. As such, preventive therapeutic strategies are anticipated which incorporate multiple therapeutic components.
At least two ocular components are known to change as part of refractive error development. The first is the crystalline lens geometry and the second is the vitreous chamber depth of the eye. In the normal process these anatomic components change in concert with each other to render the optical system of the eye appropriate for the vitreous chamber depth of the eye. It is also known by those skilled in the art that the equatorial diameter of the eye may vary relative to the axial length of the eye. Eyes which manifest myopia are often found to be more prolate in geometry and having an equatorial diameter which is smaller relative to their axial length than eyes manifesting hyperopia.
Researchers have identified the presence of a lower blood serum level of Vitamin D in individuals who develop myopia. (D. O. Mutti, Vitamin D receptor (VDR) and group-specific component (Vitamin D binding protein) polymorphisms in myopia, The Association for Research in vision and Ophthalmology, February 2011). A local release of neutraceuticals using time release nano-technology in a contact lens may have value when coupled with eye-wear borne illumination.
Chia et al. advanced the application of the use of muscarinic antagonists with their discovery of the efficacy of 0.01% atropine as contrasted with higher dosages having adverse side effects in children. (A. Chia, W. Chua, Y. Cheung, W. Wong, A. Lingham, A. Fong and D. Tan, Atropine for the treatment of childhood myopia, American Academy of Ophthalmology, 2011). The chronic need for the pharmaceutical suggests the value of time release in a contact lens and may have value when coupled with eye-wear borne illumination.
The role of peripheral defocus and peripheral illumination are believed to have an influence on the local growth factors which influence the shape of the crystalline lens, the equatorial diameter and the axial length of the eye.
Neitz et al. have developed a method and apparatus for limiting the growth of eye length. (See U.S. Patent Publication No. 2011/0313058). Although Neitz teaches the importance of wavelength modulation, the intervention is limited to filters that filter red light. (See, e.g., claim 17). Such filters fail to modulate brightness above an ambient level.
The work of Wildsoet in 2002 provided early evidence to the importance of light (including the wavelength of the light) for limiting the growth of eye length. (See C. Wildsoet, Recent insights from animal myopia research, BejingSeminar, November 2002).